1,1-Di­methyl­ethyl N-propanoyl­carbamate

Brodesser, S.; Mikeska, T.; Nieger, M.; Kolter, T.

doi:10.1107/S1600536803016520

1,1-Dimethylethyl N-propanoylcarbamate

S. Brodesser, T. Mikeska, M. Nieger and T. Kolter

The title compound, C₈H₁₅NO₃, has been obtained as a by-product of an epoxidation reaction. The molecules are linked by nearly symmetrical, bifurcated N—H

O hydrogen bonds, forming infinite chains parallel to the c axis.

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Supporting information

	Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536803016520/ob6280sup1.cif Contains datablocks global, I
	Structure factor file (CIF format) https://doi.org/10.1107/S1600536803016520/ob6280Isup2.hkl Contains datablock I

CCDC reference: 222895

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Key indicators

Single-crystal X-ray study
T = 123 K
Mean (C-C) = 0.003 Å
R factor = 0.044
wR factor = 0.111
Data-to-parameter ratio = 16.0

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No syntax errors found



Alert level A
PLAT027_ALERT_3_A _diffrn_reflns_theta_full too Low ..............      24.98 Deg.

Alert level C
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?

   1 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

Comment top

The title compound, (I), has been obtained in trace amounts as an unexpected by-product in the epoxidation of 1,1-dimethylethyl 1(S)-ethylprop-2-enylcarbamate with 3-chloroperoxybenzoic acid. It has been prepared previously on different routes (Tanaka et al., 1988; Meffre et al., 1996).

The molecular structure of (I) is shown in Fig. 1. The bond angles O1—C1—N1, O1—C1—C2, O2—C4—O3 and O2—C4—N1 are larger than 120° and range from 123.4 (2) to 126.3 (2)° (Table 1). The two carbonyl groups C1═O1 and C4═O2, as well as their substituents C2, N1, and O3, are nearly in a plane, as seen from torsion angles C4—N1—C1—C2 and C1—N1—C4—O3 (Table 1).

The molecular arrangement in the crystal structure is characterized by the presence of a nearly symmetrical bifurcated intermolecular hydrogen bond (Table 2), forming infinite chains parallel to the c axis (Fig. 2). In these chains, four molecules build a repeating unit (Fig. 3). According to Steiner (2002), this hydrogen bond can be categorized as moderately strong. The crystal structure of a related compound, viz. 2(S)—N-tert-butoxycarbonylamino-N-methoxy-N-methylbutanamide (Sawatzki et al., 2002), in which the amide carbonyl O atom of (I) is formally replaced by an N-methoxy-N-methylamide group, shows an entirely different network of hydrogen bonds.

Experimental top

Glassware was flame dried under an argon atmosphere and allowed to cool. The starting material, 1,1-dimethylethyl 1(S)-ethylprop-2-enylcarbamate, was prepared from 2(S)—N-tert-butoxycarbonylamino-N-methoxy-N-methylbutanamide (Sibi, 1993; Sawatzki et al., 2002). In brief, this Weinreb amide was reduced to the aldehyde by lithium aluminium hydride, followed by a Wittig reaction with methylene triphenylphosphoranylidene to the starting material according to a published procedure (Campbell et al., 1998). The starting material (4.77 g, 25.8 mmol) was dissolved in a mixture of dichloromethane (260 ml) and a 0.5 M aqueous solution of sodium hydrogencarbonate (240 ml). After cooling to 273 K, 70% 3-chloroperoxybenzoic acid (mCPBA) (19.08 g, 77.4 mmol) was added in small portions. The reaction mixture was stirred at room temperature for 1 h, cooled to 273 K again, and 70% mCPBA (19.08 g, 77.4 mmol) was added. After stirring for another hour, the same amount of mCPBA was added and stirring was continued overnight. The organic and the aqueous phases were separated. The organic phase was subsequently washed with a 1 M solution of sodium hydroxide, with water, and dried over sodium sulfate. After evaporation of the solvent, the resulting residue was purified by column chromatography on silica gel using hexane/ethyl acetate (5:1) as eluent. The major product was separated, and one fraction containing a substance eluting with R_F = 0.23 was further analyzed. On slow removal of the solvent, a few colourless crystals of (I) were obtained, which were suitable for X-ray analysis. Spectral data were in accordance with literature data (Tanaka et al., 1988; Meffre et al., 1996).

Computing details top

Data collection: COLLECT (Nonius, 1997-2000); cell refinement: HKL SCALEPACK (Otwinowski & Minor, 1997); data reduction: HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-NT (Sheldrick, 2001); software used to prepare material for publication: SHELXL97.

Figures top

	Fig. 1. The molecular structure of (I) showing the atom-numbering scheme and displacement ellipsoids at the 50% probability level for the non-H atoms.
	Fig. 2. The crystal structure of (I) projected along the c axis, showing the packing of the infinite chains. H atoms have been omitted except for the carbamate H atom.
	Fig. 3. Enlarged excerpt of the crystal packing, showing that four molecules build a repeating unit. H atoms have been omitted except for the carbamate H atom.

1,1-Dimethylethyl N-propanoylcarbamate top

Crystal data top

C₈H₁₅NO₃	D_x = 1.132 Mg m⁻³
M_r = 173.21	Mo Kα radiation, λ = 0.71073 Å
Tetragonal, I4₁/a	Cell parameters from 4015 reflections
a = 16.5136 (9) Å	θ = 1–25°
c = 14.9106 (8) Å	µ = 0.09 mm⁻¹
V = 4066.1 (4) Å³	T = 123 K
Z = 16	Plates, colourless
F(000) = 1504	0.30 × 0.10 × 0.05 mm

Data collection top

Nonius KappaCCD diffractometer	928 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	R_int = 0.078
Graphite monochromator	θ_max = 25.0°, θ_min = 3.1°
rotation in ϕ and ω (1°) scans	h = −19→12
13978 measured reflections	k = −19→19
1792 independent reflections	l = −17→17

Refinement top

Refinement on F²	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F² > 2σ(F²)] = 0.044	Hydrogen site location: inferred from neighbouring sites
wR(F²) = 0.111	H atoms treated by a mixture of independent and constrained refinement
S = 0.89	w = 1/[σ²(F_o²) + (0.0547P)²] where P = (F_o² + 2F_c²)/3
1792 reflections	(Δ/σ)_max < 0.001
112 parameters	Δρ_max = 0.16 e Å⁻³
1 restraint	Δρ_min = −0.15 e Å⁻³

Crystal data top

C₈H₁₅NO₃	Z = 16
M_r = 173.21	Mo Kα radiation
Tetragonal, I4₁/a	µ = 0.09 mm⁻¹
a = 16.5136 (9) Å	T = 123 K
c = 14.9106 (8) Å	0.30 × 0.10 × 0.05 mm
V = 4066.1 (4) Å³

Data collection top

Nonius KappaCCD diffractometer	928 reflections with I > 2σ(I)
13978 measured reflections	R_int = 0.078
1792 independent reflections

Refinement top

R[F² > 2σ(F²)] = 0.044	1 restraint
wR(F²) = 0.111	H atoms treated by a mixture of independent and constrained refinement
S = 0.89	Δρ_max = 0.16 e Å⁻³
1792 reflections	Δρ_min = −0.15 e Å⁻³
112 parameters

Special details top

Experimental. dx = 40 mm, 240 sec./°., 1 °., 4 sets, 324 frames, mos.= 0.816 (3) °.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å²) top

	x	y	z	U_iso*/U_eq
O1	0.30793 (9)	0.88290 (9)	0.54964 (10)	0.0444 (5)
O2	0.15566 (9)	0.92218 (9)	0.47896 (10)	0.0417 (5)
O3	0.17118 (8)	0.97578 (9)	0.33940 (9)	0.0431 (5)
N1	0.28070 (11)	0.94146 (11)	0.41442 (12)	0.0386 (5)
H1	0.3036 (12)	0.9589 (12)	0.3657 (12)	0.046*
C1	0.33142 (14)	0.90957 (13)	0.47855 (16)	0.0369 (6)
C2	0.41862 (14)	0.91102 (16)	0.45151 (17)	0.0559 (7)
H2A	0.4232	0.8893	0.3898	0.067*
H2B	0.4372	0.9680	0.4502	0.067*
C3	0.47380 (16)	0.86385 (15)	0.51136 (17)	0.0657 (8)
H3A	0.5295	0.8681	0.4892	0.099*
H3B	0.4572	0.8069	0.5117	0.099*
H3C	0.4709	0.8856	0.5724	0.099*
C4	0.19742 (15)	0.94439 (13)	0.41724 (15)	0.0370 (6)
C5	0.08313 (13)	0.98524 (15)	0.32205 (15)	0.0440 (7)
C6	0.08253 (14)	1.01637 (15)	0.22592 (14)	0.0529 (7)
H6A	0.1048	0.9749	0.1860	0.079*
H6B	0.1156	1.0655	0.2219	0.079*
H6C	0.0268	1.0287	0.2080	0.079*
C7	0.04087 (14)	0.90367 (15)	0.32768 (16)	0.0559 (7)
H7A	0.0657	0.8661	0.2848	0.084*
H7B	−0.0166	0.9103	0.3133	0.084*
H7C	0.0464	0.8819	0.3885	0.084*
C8	0.04883 (14)	1.04747 (15)	0.38598 (16)	0.0568 (7)
H8A	0.0789	1.0983	0.3798	0.085*
H8B	0.0537	1.0276	0.4477	0.085*
H8C	−0.0084	1.0568	0.3719	0.085*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
O1	0.0506 (11)	0.0489 (11)	0.0336 (10)	0.0052 (8)	0.0015 (8)	0.0060 (8)
O2	0.0411 (10)	0.0513 (11)	0.0328 (9)	−0.0047 (8)	0.0031 (8)	0.0040 (8)
O3	0.0360 (10)	0.0601 (11)	0.0333 (9)	0.0004 (8)	−0.0038 (7)	0.0089 (8)
N1	0.0339 (13)	0.0544 (13)	0.0275 (11)	−0.0009 (10)	0.0012 (9)	0.0089 (10)
C1	0.0423 (16)	0.0352 (14)	0.0332 (14)	−0.0005 (11)	−0.0018 (13)	−0.0026 (12)
C2	0.0369 (17)	0.079 (2)	0.0522 (16)	0.0008 (14)	−0.0048 (13)	0.0127 (15)
C3	0.0543 (18)	0.077 (2)	0.0662 (19)	0.0182 (15)	0.0014 (15)	0.0024 (16)
C4	0.0399 (17)	0.0378 (15)	0.0333 (15)	−0.0025 (12)	−0.0016 (13)	−0.0007 (12)
C5	0.0308 (15)	0.0584 (18)	0.0427 (15)	0.0014 (12)	−0.0017 (11)	0.0041 (12)
C6	0.0464 (16)	0.0708 (19)	0.0414 (15)	0.0032 (13)	−0.0068 (12)	0.0087 (14)
C7	0.0435 (16)	0.0662 (19)	0.0580 (17)	−0.0065 (14)	−0.0068 (13)	0.0057 (14)
C8	0.0479 (17)	0.0689 (19)	0.0535 (16)	0.0107 (14)	−0.0010 (13)	0.0012 (14)

Geometric parameters (Å, º) top

O1—C1	1.212 (2)	C3—H3C	0.9800
O2—C4	1.207 (2)	C5—C8	1.512 (3)
O3—C4	1.343 (2)	C5—C7	1.519 (3)
O3—C5	1.485 (2)	C5—C6	1.523 (3)
N1—C1	1.376 (3)	C6—H6A	0.9800
N1—C4	1.377 (3)	C6—H6B	0.9800
N1—H1	0.867 (15)	C6—H6C	0.9800
C1—C2	1.496 (3)	C7—H7A	0.9800
C2—C3	1.495 (3)	C7—H7B	0.9800
C2—H2A	0.9900	C7—H7C	0.9800
C2—H2B	0.9900	C8—H8A	0.9800
C3—H3A	0.9800	C8—H8B	0.9800
C3—H3B	0.9800	C8—H8C	0.9800

C4—O3—C5	120.47 (17)	O3—C5—C7	110.30 (18)
C1—N1—C4	126.89 (19)	C8—C5—C7	113.3 (2)
C1—N1—H1	116.3 (15)	O3—C5—C6	101.89 (17)
C4—N1—H1	116.7 (15)	C8—C5—C6	111.2 (2)
O1—C1—N1	123.5 (2)	C7—C5—C6	110.4 (2)
O1—C1—C2	123.4 (2)	C5—C6—H6A	109.5
N1—C1—C2	113.1 (2)	C5—C6—H6B	109.5
C3—C2—C1	114.7 (2)	H6A—C6—H6B	109.5
C3—C2—H2A	108.6	C5—C6—H6C	109.5
C1—C2—H2A	108.6	H6A—C6—H6C	109.5
C3—C2—H2B	108.6	H6B—C6—H6C	109.5
C1—C2—H2B	108.6	C5—C7—H7A	109.5
H2A—C2—H2B	107.6	C5—C7—H7B	109.5
C2—C3—H3A	109.5	H7A—C7—H7B	109.5
C2—C3—H3B	109.5	C5—C7—H7C	109.5
H3A—C3—H3B	109.5	H7A—C7—H7C	109.5
C2—C3—H3C	109.5	H7B—C7—H7C	109.5
H3A—C3—H3C	109.5	C5—C8—H8A	109.5
H3B—C3—H3C	109.5	C5—C8—H8B	109.5
O2—C4—O3	126.3 (2)	H8A—C8—H8B	109.5
O2—C4—N1	125.7 (2)	C5—C8—H8C	109.5
O3—C4—N1	108.03 (19)	H8A—C8—H8C	109.5
O3—C5—C8	109.18 (18)	H8B—C8—H8C	109.5

C4—N1—C1—O1	−3.9 (4)	C1—N1—C4—O2	3.3 (4)
C4—N1—C1—C2	176.0 (2)	C1—N1—C4—O3	−176.36 (19)
O1—C1—C2—C3	10.4 (3)	C4—O3—C5—C8	66.2 (2)
N1—C1—C2—C3	−169.5 (2)	C4—O3—C5—C7	−58.9 (3)
C5—O3—C4—O2	−0.7 (3)	C4—O3—C5—C6	−176.10 (19)
C5—O3—C4—N1	178.97 (17)

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1···O1ⁱ	0.87 (2)	2.18 (2)	2.943 (2)	147 (2)
N1—H1···O2ⁱ	0.87 (2)	2.26 (2)	2.933 (2)	135 (2)

Symmetry code: (i) −y+5/4, x+3/4, z−1/4.

Experimental details

Crystal data
Chemical formula	C₈H₁₅NO₃
M_r	173.21
Crystal system, space group	Tetragonal, I4₁/a
Temperature (K)	123
a, c (Å)	16.5136 (9), 14.9106 (8)
V (Å³)	4066.1 (4)
Z	16
Radiation type	Mo Kα
µ (mm⁻¹)	0.09
Crystal size (mm)	0.30 × 0.10 × 0.05

Data collection
Diffractometer	Nonius KappaCCD diffractometer
Absorption correction	–
No. of measured, independent and observed [I > 2σ(I)] reflections	13978, 1792, 928
R_int	0.078
(sin θ/λ)_max (Å⁻¹)	0.594

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.044, 0.111, 0.89
No. of reflections	1792
No. of parameters	112
No. of restraints	1
H-atom treatment	H atoms treated by a mixture of independent and constrained refinement
Δρ_max, Δρ_min (e Å⁻³)	0.16, −0.15

Computer programs: COLLECT (Nonius, 1997-2000), HKL SCALEPACK (Otwinowski & Minor, 1997), HKL DENZO (Otwinowski & Minor, 1997) and SCALEPACK, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL-NT (Sheldrick, 2001), SHELXL97.

Selected geometric parameters (Å, º) top

O1—C1	1.212 (2)	N1—C1	1.376 (3)
O2—C4	1.207 (2)	N1—C4	1.377 (3)
O3—C4	1.343 (2)	C1—C2	1.496 (3)

O1—C1—N1	123.5 (2)	O2—C4—O3	126.3 (2)
O1—C1—C2	123.4 (2)	O2—C4—N1	125.7 (2)
N1—C1—C2	113.1 (2)	O3—C4—N1	108.03 (19)

C4—N1—C1—O1	−3.9 (4)	C1—N1—C4—O2	3.3 (4)
C4—N1—C1—C2	176.0 (2)	C1—N1—C4—O3	−176.36 (19)
O1—C1—C2—C3	10.4 (3)	C4—O3—C5—C8	66.2 (2)
N1—C1—C2—C3	−169.5 (2)	C4—O3—C5—C7	−58.9 (3)
C5—O3—C4—O2	−0.7 (3)	C4—O3—C5—C6	−176.10 (19)
C5—O3—C4—N1	178.97 (17)